Enhanced antitumor efficacy by cyclic RGDyK-conjugated and paclitaxel-loaded pH-responsive polymeric micelles

Cyclic RGDyK (cRGDyK)-conjugated pH-sensitive polymeric micelles were fabricated for targeted delivery of paclitaxel to prostate cancer cells based on pH-sensitive copolymer poly(2-ethyl-2-oxazoline)-poly( d , l -lactide) (PEOz-PLA) and cRGDyK-PEOz-PLA to enhance antitumor efficacy. The prepared micelles with an average diameter of about 28   nm exhibited rapid release behavior at endo/lysosome pH, effectively enhanced the cytotoxicity of paclitaxel to PC-3 cells by increasing the cellular uptake, which was correlated with integrin α v β 3 expression in tumor cells. The active targeting activity of the micelles was further confirmed by in vivo real time near-infrared fluorescence imaging in PC-3 tumor-bearing nude mice . Moreover, the active targeting and pH-sensitivity endowed cRGDyK-conjugated micelles with a higher antitumor effect in PC-3 xenograft-bearing nude mice compared with unmodified micelles and Taxol with negligible systemic toxicity. Therefore, these results suggested that cRGDyK-conjugated pH-sensitive polymeric micelles may be a promising delivery system for efficient delivery of anticancer drugs to treat integrin α v β 3 -rich prostate cancers.